Volcanoes were named after Vulcan—the ancient Roman god of fire and metals. According to Roman legend, Vulcan lived under a volcanic island off the coast of Italy. He often built huge fires in his forge deep in the earth. Smoke and sparks flew from Vulcan’s chimney as he made his weapons. “Volcano” comes from Volcanus, the latin word for Vulcan. We now know that pressure and heat deep underground produce hot, liquid rock called magma. Volcanic eruptions occur when magma and hot gases are forced up through the earth’s crust.